The long term objective of this project is to develop flow cytometric devices and procedures for rapid, quantitative classification of chromosomes according to shape and/or fluorescent banding pattern. These developments will contribute to cytogenetic studies by allowing quantitation of important cytogenetic endpoints such as: 1) polyploidy, trisomy, and monosomy, 2) chromosomal variants such as stain content polymorphisms, and 3) structural rearrangements such as fragments, deletions, dicentrics, and translocations. In this project, we propose to continue development of flow cytometric procedures for measurement of the distribution of fluorescent dye(s) along isolated mammalian chromosomes. Specifically we will: complete development of a slit-scan flow cytometer capable of measuring and classifying chromosomes according to shape at rates up to 1000/sec with spatial resolution approaching 2.5 Mum; develop fringe-scan flow cytometry to allow chromosome scanning and classification with spatial resolution approaching 0.3 Mum, and develop improved chromosome preparation and staining procedures to produce enlarged, fluorescently banded chromosomes. As these new chromosome scanning techniques are developed, we will use them for quantification of the frequency of randomly occurring aberrant chromosomes in mutagen treated cell populations and for classification of homogeneously chromosomes according to shape and/or banding pattern.